Output controlling method and device for internal combustion engines

ABSTRACT

A method of and a device for controlling the output of an internal combustion engine, in which a mixture in an amount corresponding to the amount required for the full load operation of the engine is caused to flow into each cylinder in the suction stroke, even in the case of partial load operation, and, in the compression stroke, the amount of mixture required for the particular load of the engine is remained in the cylinder and the remaining part thereof is caused to flow back into the suction system from the cylinder.

United States Patent 11 1 1 11 3,919,986

Goto 5] Nov. 18, 1975 [5 OUTPUT CONTROLLING METHOD AND 1,384,133 7/1921Howe 123/105 DEVICE FOR INTERNAL COMBUSTION 1,623,589 4/1927 Granath123/ 105 3.416.502 12/1968 Weiss 123/75 E ENGINES Inventor: Kenji Goto,Shizuoka, Japan Toyota Jidosha Kogyo Kabushiki Kaisha, Aichi, JapanFiled: Oct. 3, 1973 Appl. No.: 403,158

Assignee:

Foreign Application Priority Data July 9, i973 Japan 48-77251 ReferencesCited UNITED STATES PATENTS 1.2/1912 Cross 123/75 E PrimaryExaminer-Wendell E. Burns Assistant ExaminerDavid Reynolds Attorney,Agent, or FirmSpensley, Horn and Lubitz ABSTRACT 5 Claims, 5 DrawingFigures U.S. Patent Nov. 18, 1975 Sheet1of2 3,919,986

FIG.2

US. Patent Nov. 18, 1975 Sheet 2 of2 3,919,986

FIG

FIG.4

TDCH

BDCH

CRANK ANGLE 8 BDCI BDCH

TDCI

Fl G. 5

BDCI

PISTON STROKE V OUTPUT CONTROLLING METHOD AND DEVICE FOR INTERNALCOMBUSTION ENGINES BACKGROUND OF THE INVENTION This invention relatesgenerally to the control of the output of internal combustion engines,and particularly to a method of and a device for controlling the outputof internal combustion engines, in which a mixture once sucked into eachcylinder in an amount corresponding to the amount required for the fullload operation of the engine, even in the case of partial loadoperation, ispartially caused to flow back into the suction pipe in thecompression stroke, the amount of mixture flowing back into the suctionpipe being controlled thereby to control the output of the engine.

The output of internal combustion engines, e.g. reciprocating internalcombustion engines, has generally been controlled by a throttle valvewhich is provided in the suction pipe between the suction valve and thecarburetor Venturi at a location downstream of said carburetor Venturiand which is opened and closed by the accelerator pedal operativelyinterlocked therewith.

The conventional internal combustion engines of the type described havehad. the following disadvantages: Namely, (l the amount of the residualgas is large because the combustion gas is sucked into the suctionsystem under the effect of the vacuum pressure occurring in said suctionsystem during the overlapping period of the opening strokes of thesuction valve and exhaust valve; (2) a fluctuation of the vacuumpressure in the suction stroke under varying load on the engine resultsin a fluctuation of the amount of liquid fuel in the suction pipe andcontrol of the air fuel ratio during the period of this fluctuation isdifficult; (3) in the suction stroke, the vacuum pressure in the suctionpipe increases the pumping loss; and (4) the throttle valve closes thesuction pipe at the deceleration of the engine, so that a shortage ofthe intake air results and unburned gases are released into theatmosphere.

SUMMARY OF THE INVENTION According to the present invention, an amountof mixture corresponding to the amount required for the full loadoperation of the engine, even in the case of partial load operation, issucked into each cylinder in the suction stroke and, in the compressionstroke, the mixture is partially caused to flow back into the suctionpipe according to the load on the engine, whereby the output of theengine is controlled.

To this end, according to the invention each cylinder of the engine isprovided with at least two ports which are respectively communicatedwith the suction pipe and opened and closed by valve means and the like,and a conduit communicating at least one of said ports with the suctionpipe is provided therein with a throttle valve whose opening iscontrolled by an output controlling mechanism such as an acceleratorpedal and a conduit communicating at least one other port with thesuction pipe is used for passing an amount of mixture I corresponding tothe amount required for the full load operation of the engine, in thesuction stroke the amount of mixture corresponding to the amountrequired for the full load operation being sucked into the cylinder fromsaid latter port and, in the compression stroke, said latter port beingclosed and the mixture in the cylinder being partially caused to flowback into the suction pipe from said former port according to the de- 2gree of opening of said throttle valve, whereby the output of the engineis controlled.

An object of the invention is to provide a method of and a device forcontrolling the output of internal combustion engines, which does notmake the internal pressure of the suction pipe extremely low, whichminimizes the pumping loss and which prevents the exhaust gas from beingsucked into the suction system under the effect of the vacuum pressurein said suction system.

Another object of the invention is to provide a method of and a devicefor controlling the output of internal combustion engines, whichincreases the amount of mixture in proportion to the amount of residualgas at the deceleration of the engine from a high speed phase ofoperation and does not cause misfire.

Still another object of the invention is to provide a method of and adevice for controlling the output of internal combustion engines, whichmaintains the amount of mixture supplied from the suction port constantindependently of the fluctuation of the load on the engine, whichreduces to a minimum the fluctuation of the amount of liquid fuelpassing in the suction pipe and facilitates control of the air fuelratio.

' Still another object of the invention is to provide a method of and adevice for controlling the output of internal combustion engines, whichprevents misfire or after-burning at the start of deceleration due tooverpitch arising from the gasification of liquid fuel and whichprevents overheatin'g of an exhaust gaspurifying device when such deviceis used with the engine.

A further object of the invention is to provide a method of and a devicefor controlling the output of internal combustion engines, which duringoperation of the engine under low loads, causes the mixture torecirculate repeatedly between the suction system and the cylinder,whereby the atomization of the mixture is promoted, the combustionchamber of the cylinder is cooled by the recirculating mixture, thesuction gas temperature and therefore the highest combustion temperatureis lowered owing to the reduced pumping loss, and the discharge of NOxis decreased.

An additional object of the invention is to provide a method of and adevice for controlling the output of internal combustion engines, inwhich during the compression stroke, the compressed gas is caused toflow back into the suction system from the cylinder, whereby swirling ofthe gas in the combustion chamber is enhanced, the combustion rate isincreased and thereby the efficiency of the engine is increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 3 are sectional views of areciprocating four-cycle internal combustion engine in which the presentinvention is embodied, FIG. 1 being a view of the engine in the suctionstroke, FIG. 2 being a view of the engine in the compression stroke, andFIG. 3 being a view of the engine in the exhaust stroke;

FIG. 4 is a characteristic diagram illustrating the operations of thevalves of the internal combustion engine shown in FIGS. 1 to 3; and

FIG. 5 is an indicator diagram (P-V diagram) of the internal combustionengine.

DESCRIPTION OF THE PREFERRED EMBODIMET With reference to FIGS. 1 to 3, acylinder head 1A of a cylinder 1 of an internal combustion engine isprovided with a suction port 2A, a suction valve 2 for 3 opening andclosing said port 2A, an exhaust port 3A, an exhaust valve 3 for openingand closing said port 3A, a back-flow port 4A and a back-flow valve 4for opening and closing said port 4A.

A conduit 5A diverged from a suction pipe 5 is connected to theback-flow port 4A and the suction pipe 5 is connected to the suctionport 2A.

The conduit 5A is provided therein with a throttle valve 6 by which theflow in said conduit is controlled. The throttle valve 6 is operativelyinterlocked with an output controlling mechanism, such as an acceleratorpedal, (not shown) to be operated thereby in such a manner that it isangularly displaced in a closing direction as the load on the engineincreases and in an opening direction as the load on the enginedecreases. Reference numeral 7 designates a piston.

The suction valve 2, the exhaust valve 3 and the back-flow valve 4respectively are operated by operating means, such as cams, (not shown)which are operatively interlocked with the output shaft of the engine,in the manner shown in the characteristic diagram of FIG. 4. In thecharacteristic diagram of FIG. 4, the axis of abscissa is scaled by thecrank angle 0 of the engine and the axis of ordinate by the valve lifth, and the curve A represents the operational characteristic of theexhaust valve 3, the curve B the operational characteristic of thesuction valve 2 and the curve C the operational characteristic of theback-flow valve 4. Namely, the exhaust valve 3 starts opening from apoint immediately before the piston 7 reaches its bottom dead center Iof the piston 7 and is closed at a point immediately after the piston 7reaches its top dead center I. The suction valve 2 starts opening at apoint immediately before the piston 7 reaches its top dead center I andis closed at a point immediately after the piston reaches its bottomdead center II. The back-flow valve 4 starts opening at a pointimmediately before the piston reaches its bottom dead center II and isclosed at a point about 130 of the crank angle from the bottom deadcenter II of the piston, the lift of said valve being largest at a pointwhere the crank angle is 60.

Now, the operation of the internal combustion engine described abovewill be described.

The suction valve 2 is opened at the point immediately before the piston7 reaches its top dead center (TDC) and a mixture is sucked into thecylinder 1. The volume of the mixture is the same as that required atthe full load operation of the engine, even in the case of not full loadoperation, and the pressure thereof is the atmospheric pressure (or thepressure of supercharged mixture when a supercharger is used). Theflow-back valve 4 is opened at the point immediately before the piston 7moving down from its top dead center I reaches its bottom dead center(BDC) II and closed at the point when the piston 7 advances from itsbottom dead center II about 130 in terms of the crank angle. The suctionvalve 2 is closed at the point immediately after the piston reaches itsbottom dead center II. Thus, it will be understood that the mixture inthe cylinder 1 is forced back into the conduit 5A and suction pipe 5through the back-flow port 4A in an amount according to the degree ofopening of the throttle valve 6 in the initial stage of the compressionstroke. (No mixture is forced back into the conduit 5A when said conduitis closed by the throttle valve 6.)

As a consequence, the engine generates an output corresponding to theamount of mixture remaining in 4 the cylinder I and operates along theP-V curve shown in the diagram of FIG. 5.

The mixture forced back into the conduit 5A is partially or entirelysucked into the cylinder 1 at the next suction stroke through thesuction pipe 5 and the suction port 2A and the mixture thus sucked isfurther partially recirculated in the passage formed by the cylinder 1,the conduit 5A and the suction pipe 5.

Although in the embodiment described and illustrated herein the openingand closing of the suction port 2A and the back-flow port 4A areeffected by means of valves, it should be understood that the same maybe effected by any other means. It should also be understood that whilethe present invention has been described herein as applied to afour-cycle reciprocating internal combustion engine, it is generallyapplicable to other types of internal combustion engine, including areciprocating two-cycle internal combustion engine or rotary pistonengine.

I claim:

1. A method of controlling the output of a four-cycle internalcombustion engine, comprising supplying an amount of mixturecorresponding to the amount required at the full-load operation of theengine into a cylinder of the engine at the suction stroke, and at thecompression stroke causing an amount of mixture in excess to the amountrequired for operation of the engine to flow back from the cylinder intoa suction pipe by the action of the piston in said cylinder, saidmixture in excess being delivered only to the suction pipe coupled tothe corresponding cylinder and being substantially confined for usewithin said corresponding cylinder, whereby the output of the engine iscontrolled.

2. The method of claim 1 wherein:

said amount caused to flow back is controlled by throttling saidflow-back of said excess mixture such that the amount of said flow-backentering a conduit communicating with said suction pipe is controlled,said throttling of said flow-back being achieved by a throttle disposedwithin said conduit.

3. A device for controlling the output of an internal combustion enginecomprising a suction port from which an amount of mixture correspondingto the amount required for the full load operation of the engine issupplied into a cylinder, a back-flow port provided separately from saidsuction port, a conduit communicating the cylinder with a suction pipethrough the back-flow port in a direct fashion such that substantiallyall of said mixture delivered through said conduit to said suction pipeis supplied to said cylinder corresponding to said conduit and suctionpipe, said backflow port being opened only at a specific stage of thecompression stroke of the engine, and a throttle valve provided in theconduit and being operated such that said throttle is angularlydisplaced in a closing direction as the load on the engine is increased.

4. The device of claim 3 wherein: said internal combustion engine is afour cycle engine; and said backflow port is opened during thecompression cycle between bottom dead center and 130 after bottom deadcenter, said back-flow port having a maximum opening at after bottomdead center. 5. The device of claim 3 wherein: said suction pipe andsaid conduit are exterior to the walls of said cylinder.

1. A method of controlling the output of a four-cycle internalcombustion engine, comprising supplying an amount of mixturecorresponding to the amount required at the full-load operation of theengine into a cylinder of the engine at the suction stroke, and at thecompression stroke causing an amount of mixture in excess to the amountrequired for operation of the engine to flow back from the cylinder intoa suction pipe by the action of the piston in said cylinder, saidmixture in excess being delivered only to the suction pipe coupled tothe corresponding cylinder and being substantially confined for usewithin said corresponding cylinder, whereby the output of the engine iscontrolled.
 2. The method of claim 1 wherein: said amount caused to flowback is controlled by throttling said flow-back of said excess mixturesuch that the amount of said flow-back entering a conduit communicatingwith said suction pipe is controlled, said throttling of said flow-backbeing achieved by a throttle disposed within said conduit.
 3. A devicefor controlling the output of an internal combustion engine comprising asuction port from which an amount of mixture corresponding to the amountrequired for the full load operation of the engine is supplied into acylinder, a back-flow port provided separately from said suction port, aconduit communicating the cylinder with a suction pipe through theback-flow port in a direct fashion such that substantially all of saidmixture delivered through said conduit to said suction pipe is suppliedto said cylinder corresponding to said conduit and suction pipe, saidback-flow port being opened only at a specific stage of the compressionstroke of the engine, and a throttle valve provided in the conduit andbeing operated such that said throttle is angularly displaced in aclosing direction as the load on the engine is increased.
 4. The deviceof claim 3 wherein: said internal combustion engine is a four cycleengine; and said back-flow port is opened during the compression cyclebetween bottom dead center and 130* after bottom dead center, saidback-flow port having a maximum opening at 60* after bottom dead center.5. The device of claim 3 wherein: said suction pipe and said conduit areexterior to the walls of said cylinder.